The objective is the elucidation of the relationship between abortive measles virus infection in human erythroid cells induced to differentiate and the effect this viral infection has on cellular gene expression. The specific aim is to clarify the conditions whereby measles virus causes enhanced hemoglobin synthesis in a cell already chemically stimulated to synthesize hemoglobin and the effect this induction state has on measles virus production. To achieve this aim, viral and cellular protein synthesis and viral and globin messenger RNA will be analyzed and correlated with the hemoglobin induction state of the cells. Suspension cultures of K562 cells will be induced to synthesize hemoglobin by addition of hemin to the culture medium. Prior to and after hemin addition, the cells will be challenged with measles virus. Viral and cellular growth kinetics will be correlated with protein synthesis and hemoglobin induction. Viral RNA's will be isolated from a non-productive infection and compared with viral RNA's from a productive infection. Hemoglobin induction in the presence of viral infection will be analyzed at the level of globin transcription. The rate of globin transcription, level of globin mRNA accumulation and turnover rate of globin mRNA will be analyzed by means of cloned hybridization probes specific for each of the human embryonic, fetal, and adult globin genes.